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Title:	Mechanisms of membrane fouling during the clarification of glycerine-rich solutions
Authors:	Indok Nurul Hasyimah Mohd Amin (P42488)
Supervisor:	Abdul Wahab Mohammad, Prof. Ir. Dr.
Keywords:	Glycerin Membranes (Technology) Fouling Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	22-Mar-2012
Description:	In the oleochemical industry, glycerinerich solutions (sweetwater) are generally produced as a major byproduct of the hydrolysis process. According to the sample analysis from a local oleochemical company, sweetwater contains a mixture of glycerol (25.8%) and water (70.1%) as well as impurities such as fatty acids (FA), unreacted triglycerides (TGs), inorganic salts and matter organic nonglycerol (MONG) (4.1%). Separation of glycerine from sweetwater appears attractive due to the demand of glycerine as a product. Ultrafiltration (UF) could be an option for this purpose. However, severe fouling during the UF process was observed which reduced the flux drastically due to the presence of FAs and TGs. The present research was undertaken to investigate the extent of membrane fouling caused by long chain FAs and TGs as well as their combined effects to fouling. The effect of parameters such as membrane surface chemistry, molecular weight cut off (MWCO), temperature, different type of FA and feed characteristic to flux behavior were investigated. Experiments were carried out in deadend unit. The first part of this research revealed that the addition of FAs to the glycerinerich solutions caused significant flux decline, even though the MW of FAs is much smaller than the membrane MWCOs. Moreover, experimental data showed that the polyvinylidenfluoride (PVDF) membrane exhibited higher fluxes and lower fouling propensity compared to the polyethersulfone (PES) membrane, mainly attributed to the surface chemistry of the membrane material itself. The relative flux of PES membranes with larger MWCO decreased by up to 33% compared to 5.6% with smaller ones, but did not vary significantly with operating temperature. Further, the degree of flux decline for both membranes follows the order of mixture (no fatty acid) < (palmitic acid) < (stearic acid) < (oleic acid) and the finding was associated with the rejection data. The palmitic, stearic and oleic acid were rejected to the extent of 15.6, 35.8 and 41.4%, respectively. It is inferred that palmitic acid diffuses faster and suffer less fouling. The second part of this research examined the potential effect of TGs on fouling both by itself and in combination with FAs. It was found that in glycerolwater solutions containing TGs, the contribution of the solute to fouling was more severe than that of TGsFA mixtures, with lower permeation rates being shown. The analysis demonstrated that the ability of FAs to diffuse in the solution affect the oil droplets size and the fouling behavior. The average size of oil droplets in glycerolwater plus TGs was 63.25 μm, which is considerably larger than the droplets in TGsFA mixture (44.77 μm). Moreover, the feed characteristic played an important role in the fouling potential for both studies. Both membranes underwent severe fouling at low pH due to association of FAs and greater deposition of oil droplets on the membrane surface as well as near the pore entrance. It was found that the combined model was able to predict well the flux decline behaviour and exhibited R2 more than 0.90 for all cases. However, Hermia model only showed a good correlation with the experimental data of feed solutions plus FA while poor fitting to feed solution plus TG (R2 < 0.9).,Certification of Master's / Doctoral Thesis" is not available
Pages:	269
Call Number:	TD427.F68I537 2012 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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